class People:
    name = ''
    age = 0
    __weight = 0

    def __init__(self,n,a,w):
        self.name = n
        self.age = a
        self.__weight = w
    def speak(self):
        print('%s 说： 我 %d 岁'%(self.name,self.age))

class Student(People):
    grade = ''
    def __init__(self,n,a,w,g):
        People.__init__(self,n,a,w)
        self.grade = g
    def speak(self):
        print("%s 说: 我 %d 岁了，我在读 %d 年级"%(self.name,self.age,self.grade))
s = Student('Ken',10,60,3)

s.speak()